Have a few questions before I give this a grow

Okay so I've been reading about how to do this for a while now, and in a few weeks I should be able to give it a shot. But I have a few questions/ideas and I'm wondering what would be best with my budget... I'm going to have 300-500$ to work with... Initially I wanted to go with a grow tent, but venting out of my room may be an issue and the overall cost would be more than double what I have to work with... So I am either going to A. Make those DIY Grow Chambers out of Rubbermaid Bins, CFLs, PC Fans up near the lights for exhaust, passive intake on the opposite side at the bottom etc. The guide only has 6 lights bit I'm going to get the biggest bins I can and try to fit 8 at the very top and I'll adjust the heights of the plants as needed. It states that because the area is so small that the lumens per sq ft will allow for 4-6 plants to grow? If not that I was maybe going to do 2 or 3 pc grows at a time with the biggest cases I can find and autoflowers with 4 of the biggest cfls i can fit per case, using pc fans for intake and exhaust. Orrr I was wondering if I could do a closet grow but venting would still be an issue. Closet is approx 2'W x 15'L x 12' H, halfway up there's a wodden board that almost cuts the top 4 feet completely off with the pole to hang clothes underneat. I could hang a 400 W MH/HPS from there easy, and section off an area of the closet with plywood or something and paint the entire area flat white or line it with mylar perhaps. So I would be looking at a 2'W x ?'L x 6.5'H area, sealing it off towards the top could be an issue... But I'm wondering if with an area this big I have to worry about venting much? I can keep one of the sliding doors open and have plenty of air circulation + clean air coming into the room itself I'm just worried about temps/odor and light leaks due to the top not being sectioned off from the rest of the closet? With a 6" cool tube reflector could I somehow have my 6" inline fan pulling through the carbon filter, my cool tube to cool the light, and vent it out the top of the grow area and out the other side of the closet? And I can cut holes at the bottom where I section it off for passive intake, I'm just worried about heat issues. Any help would be appreciated.

p.s. would leaving the top of the area open help to keep it cooled down or would this be counter productive due to light leaks? then I could just run an inline fan/carbon filter out of my closet and be golden. Can post pics if needed just too lazy and baked atm. Also I have central air which gives me a fair amount of control over the room temp, so I'm wondering if that would help at all? I have no idea how the heat from a 400w will effect the actual room temp.
 
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